300540194domain: NAppears in sequencesa(n) = binomial(2n+1, n+1) - 1.at n=15A010763Central binomial coefficient - 1.at n=31A014495Number of nonempty subsets of {1,2,...,n} in which exactly 1/2 of the elements are <= (n-1)/2.at n=31A047171Moebius transform of A001405 (binomial(n, floor(n/2))).at n=30A062791